Evaluation de l’activité antioxydante des extraits des feuilles de Aphania senegalensis (Sapindaceae) et de Saba senegalensis (Apocynaceae)

Les plantes traditionnelles présentent généralement de nombreuses propriétés thérapeutiques. L’objectif de la présente étude consistait à évaluer l’activité antioxydante des extraits des feuilles de Aphania senegalensis et de Saba senegalensis par spectrophotométrie moléculaire au moyen des méthodes de piégeage des radicaux libres 2,2-diphényl-1-picryl-hydrazyle (DPPH•) et acide 2,2’-azino-bis-(3-éthylbenzothiazoline-6- sulfonique) (ABTS+•). Une extraction éthanolique des feuilles de ces deux plantes a été effectuée au Soxhlet. Les deux extraits secs, redissouts dans de l’eau, ont été fractionnés en utilisant successivement l’hexane, le dichlorométhane et l’acétate d’éthyle. Les propriétés antioxydantes des extraits et celles de leurs différentes fractions ont été évaluées à différentes concentrations : 5, 10, 25 et 150 μg/ml. Les pourcentages d’inhibition (PI) expriment l’effet antioxydant mesuré. Une activité de piégeage des deux radicaux libres a été associée aux deux extraits et à l’ensemble des fractions. Pour les tests d’inhibition de l’absorbance du radical DPPH•, les PI ont varié de (22,20±0,03)% à (91,30±0,08)%. Avec le radical ABTS+•, les PI ont varié de (54,37±0,02)% à (99,13±0,01)%. Les extraits éthanoliques des feuilles de Aphania senegalensis et de Saba senegalensis et leurs différentes fractions présentent ainsi un pouvoir antioxydant.© 2015 International Formulae Group. All rights reserved.Mots clés: Plante médicinale, ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6 sulfonic acid)), DPPH (2,2- diphényl-1-picryl-hydrazyle), spectrophotométrie moléculaireEnglish Title: Antioxidant activity of leaves extracts of Aphania senegalensis (Sapindaceae) and Saba senegalensis (Apocynaceae)English AbstractSeveral therapeutic properties are often associated with traditional plants. The antioxidant properties of Aphania senegalensis and Saba senegalensis leaf extracts were evaluated by molecular spectrophotometry and using two radical scavenging methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and 2,2’-azino bis(3- ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The leaves of each plant were extracted with ethanol  using a Soxhlet extractor apparatus. The two dry ethanolic extracts were dissolved in water then fractionated using successively hexane, dichloromethane and ethyl acetate. The antioxidant activities of the extracts and their different fractions were determined at various concentrations: 5, 10, 25 and 150 μg/ml. The antioxidant capacity was expressed as percent inhibition (PI). The extracts and their different fractions scavenged DPPH• and ABTS+• free radicals. The DPPH assay showed PI varying from 22.20±0.03% to 91.30±0.08%. With the ABTS+• radical, the PI varied from 54.37±0.02% to 99.13±0.01%. The ethanolic extracts of Aphania senegalensis and Saba senegalensis as well as their fractions showed antioxidant capacities.© 2015 International Formulae Group. All rights reserved.Keywords: Medicinal plant, ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6 sulfonic acid)), DPPH (2,2-diphenyl-1-picrylhydrazyl), molecular spectrophotometr

Pathways to Resilience in Semi-arid Economies (PRISE) CARIAA consortium report February 2014 - November 2018

PRISE (www.prise.odi.org) (2014–2018) was funded through the Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA) programme, launched by the International Development Research Centre (IDRC) and the Department for International Development (DFID) in 2013, to fund adaptation research on three ‘hotspots’ of climate vulnerability: glacier-fed rivers, mega-deltas, and semi-arid lands (de Souza et al., 2015). ‘Hotspots’ are defined as areas where a strong climate signal coincides with a large concentration of poor, vulnerable or marginalised people. PRISE developed projects in seven countries with semi-arid regions: Senegal, Burkina Faso, Kenya, Tanzania (until 2015), Pakistan and Tajikistan and Kyrgyzstan (since 2016). CARIAA is also rooted in progressive research for development principles, including knowledge co-creation (Harvey et al., 2017) and transdisciplinarity (Cundill et al., 2018), and this is reflected in the approaches and methodology employed by PRISE.This report summarises: the key thematic, national and global findings and policy recommendations; related engagement activities and stories of impact; the approach taken by the consortium and how it was set up and managed; the monitoring of outcomes; the lessons learned; and next steps for how the research findings and recommendations can be used to inform future programming and the climate adaptation and ‘leave no one behind’ agendas

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

RPE

Meeting: Productive Strategies for Poor Rural Households to Participate Successfully in Global Economic Processes, 17-18 May 2006, Dakar, SNMeeting: Stratégies productives développées par les ménages pauvres pour participer efficacement aux processus économiques globaux, 17-18 mai 2006, Dakar, SNThis report combines results of a regional scan focusing on the Sahel belt of West Africa and a more in-depth country study focusing on Senegal. The aim is to prepare an agenda of priority research for the IDRC Rural Poverty and Environment Programme Initiative (RPE) towards the development of networks, partnerships and communities of practices, in order to enhance livelihoods of the poor, including those living in fragile or degraded uplands and coastal ecosystems. Results of the scan are organized as tables, with column headings throughout: Key Findings; Views of local stakeholders; Comments and analysis; New narrative

Rapid rural appraisal and post-production systems research : a training experience : report of a training workshop held in Senegal July 30 - August 8, 1989

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